Testing apparatus for safety mechanism for doors



April 12, 1960 S. A. HORNUNG TESTING APPARATUS FOR SAFETY MECHANISM FORDOORS Filed July 19. 1957 "I" @NFI ww.

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Br l ATTORNEY April 12, 1960 s. A. HORNUNG 2,932,365

TESTING APPARATUS FOR SAFETY MECHANISM FOR DooRs Filed July 19, 1957 2Sheets-Shea?I 2 w y r M mw :A 6 mrlfAAis m m M- Tel I l l IIRK 4 J M I II IIAH=T||EX d. Vn w H|||I|||||||E\ G. lllllllll J 6 MM -IHA f/,ll -J fM @11:11: WIIIIL? F m A I l l I l :Af lllllllr H Bz um TESTING-APPARATUS FOR SAFETY MECHA- NISM FOR DOORS Stephen Anthony Hornung,NewYork, N.Y., assignor to Otis Elevator Company, New York, NX., acorporation of New Jersey Application July 19, 1957, Serial No. V672,9289 claims. (ci; 187,548)

The invention relates to a` device for monitoring safety mechanism, suchas'safety mechanism for protecting againstv closing doors of elevatorinstallations. It' is commonpractice in present day passenger elevatorinstallations, where the closing of the'doors is etected automatically,to provide safety mechanism to avoid striking a transferring passengerwith a clos-ing door. Automatically controlled doors provided with'safety mechanism may be closed at speeds faster than would otherwise bepractical, which is desirable from a service viewpoint. However, if thissafety mechanism` becomes inoperative there is the likelihood that atransferring passenger may be struck with considerable force by aclosing door.

If the operation of the safety mechanism given priority overelevator'operation, when a safety mechanism failure occurs, thedoors'may be retained in open position. This results in the carremaining inoperativeat a oor. As an alternative, the doors may beclosed at a slower speed after' they have remainedfopen an .abnormallylong time. However, in automatically controlled elevators if the failures of an intermittent nature it may not be brought to the attention ofservice personnel Yfor s ome time. When notice of the poor elevatorresponse is obtained, much time may be spent before the .cause is foundto be inoperative safety mechanism. AThis .results in reduced elevatorefficiency.Y

The prompt reporting of the inoperativeness or lack .of sensitivityofthe safety mechanism allows the door to be closed at reduced speed atthe expiration of normal .door open time. and pinpoints .the source'ofthe trouble immediately'. Also, ya test of the sensitivity of the safetyFCC.

alarm is initiated and the speed of the doors in closing is reducedbelow normal closing speed. In carrying out the invention, according tothe arrangement which will'be described, the safety mechanism'isstimulated a predetermined minimum amount to approxi.-l

, mate the effect on the safety mechanism of a persorrorv object in thepath of movement of the doors in'closingl Features and advantages of theinvention will be seen` from the above and from the followingdescription of operation when considered in' conjunction with the draw#ings in which: l

Figurel is an "across-the-line simplified wiring diagram of a portion ofelevator power and vcontrolcircuits;` 'Figure 2 is an across-the-linevsimplified wiring dia-` gram of one form of door protective mechanismwhich' together with the control circuits of Figure 1 embodies the"invention;

' Figures 3, 4 and 5 are across-the-line simplified wiring diagrams forother forms of door protective mechanism to which the invention isapplicable; and,

Figures 1s, 2s, 3sA and 4s are spindle sheets for use inside-by-side'alignment with Figures l, 2, 3 and 4 respec-y tively, forlocating the coils and contacts of these circuits. In View of the simplecircuit involved, no spindle sheet is shown for the wiring diagram ofFigure 5.

` For convenience, the invention will be described as I applied to thesafety mechanism of the patent toW. H.

.mechanism before it is required to function minimizes 'the danger ofinjury'to passengers and makes practical :the use of preventivemaintenance. All other factors remaining equal, this results in lesscostlymaintenance `and more efficient elevator service. It is,therefore, an object of the invention to provide .fa device whichdetects and reports .the -inoperativeness or faulty operation ofelevator door safety mechanism. Another object of the invention is toprovide a device :which will test the operation -of the safety mechanism.at a predetermined level of sensitivity before the safety mechanism isrequired to function.A l

Another object of the invention is to provide a device which will reducethe speed of vthe doors in closing ybelow the -normal closing speed,whenever the safety mechanism is detected as being inoperative orinsensitive. A further object of the `invention is to maintain an alarmindication and the reduced door closing speed fonce they are initiated,until the car departs from that iloor at which the inoperativeness ofthe safety mechanism was detected, even though the safety mechanism:again become operative. Y

The invention involves a device to cause false operation of the'safetymechanism in order to test its effectivemess. Ifthe. safety mechanismfails to false operate, an i' Bruns et al., No. 2,634,828, granted April14, 1953, with particular reference to the circuits of Figure 4. Theelectromagnetic switches employed'in the circuits v shown in Figures lthrough 5 are designated as follows;

B-Safety mechanism switch DC-Door close switch y DE-Door speed switchDO-Door open switch DP--Door protective relay DFX- Auxiliary doorprotective relayv vDR-Door control switch FR- Flicker relayMR-,Monitoring relay NT-Hall time switch KNT-Auxiliary hall time relayThroughout the description which follows, these letters willbe appliedto the coils of the above designated switches and, with Vreferencetonumerals appended thereto,to the contacts of these switches. Theelectromagnetic switches are illustrated in deenergized condition. Doorcontrol switch DR is a latching type switch and is illustrated in resetcondition.

Referring iirst to Figure 1, the door power and control circuits areconnected to direct current supply lines designated W+ and W-. Carrunning relay FE (not shown) is energized incident to starting the carand is deenergized incident to stopping the car. Door relay GHI (notshown) is energized incident to opening the door and remains energizeduntil the door is in fully closed position. Field and brake switch H notshown) is energized incident to starting the car and is deenergized whenthe car is stopped. l

Clar position-indicator lamps LPl and LPS are provided, one foreach'iloor served by the car and may be located ina panel at thebuilding lobby. The alarm buzzer is designated BZ and may also belocated at the lobby. Contacts CLI to CL3 and CB1 to CBS are provided,one CL contact and one CB contact for each oor served by the car.Brushes b1 and b2 engage the CL and CB contacts, respectively, inaccordance with car movement 'to prepare the car position indicator lampLPand buzzer BZ circuits Yfor the floor at which the car is to stop.

Doorfopen lim-it switch DOL, door close limit switch DCL and door speedlimit switch DEL are actuated by Patented Apr. 12. 1960.

door movement and are illustrated for the closed position of the door.

Referring to Figure 2, the door protective circuits are connected to asource of singlephase alternating current represented by wires W11 andW12. SGT- and DPDT are constant voltage transformers for providing thedesired value of alternating current voltage. The car door sight guardCSG and the car door strike jamb post guard CPGV are connected to theungrounded side of the secondary winding of transformer DPDT, thusshielding the tubes from unwanted operation due to ground potential. Thehoistway door sightgu'ardsHSG and the hoistway door strike jarnb post Aare connected to the ungrounded side of the secondary winding oftransformer SGT, thus shielding the doors against unwanted operation asthey near closed positions. For simpliity,the hoistway door postguardsHPG and sight guards HSG are shown for only one licor in thebuilding.

Also for simplicity, the circuit for one protective tube DPT and itsassociated apparatus is shown instead of the three protective tubes DPTland DPTS and their respective associated apparatus shown and describedin connection with Figure 4 of the BrunsgPatent No. 2,634,- 828. Anadjustable point on voltage divider resistor RVD for the tube isconnected by way of current limiting resistor RIB to the controlelectrode DPTE and conductive spot CS of the tube. The antenna CA forthe tube also is connected to the control electrode DPTE and conductivespot CS. Direct current is provided through rectifier EDP for theanode-cathode circuits of the tube, approximately 150 volts beingobtained with 120 R.M.S. volts from the transformer secondary windingwhich is insulicient in itself to cause a breakdown of the tube. Aiilter network is provided by condensers QF1 and QF2 and resistor RF. Toprevent any undesirable effect on the tube by action of stray fields,shielded conductors are employed with the shields connected to ground asindicated at points SGR. The Vtube is fired by eifecting an increase inantenna to ground capacity by the body capacity to ground of a person inthe zone of inuence of the antenna. The physical construction of theprotective mechanism is more fully illustrated and described in theaforementioned Bruns Patent No.

The manner in which the doors are controlled may vary considerably. Inthe particular circuits illustrated in Figure 1, the doors openautomatically as a stop is made at a landing and close automaticallyupon the expiration of a given time interval. Auxiliary hall time relayXNT and hall time switch NT are both operated during the running of thecar. As the car arrives at the landing at which the stop is being made,field and brake switch H deenergizes. Contacts H1 separate to disconnectthe coil of auxiliary hall time relay XNT from the supply lines. Thedeenergization of this relay is delayed by the discharge of condenserQXNT. Contacts H2 close to complete a circuit by way of contacts XNT2for the set coil of door control switch DR. Switch DR latches itself inoperated condition. Contacts DRZ close to complete a circuit by way ofdoor open limit switch DOL for the coil of door open switch DO. ContactsDOS and D06 close and contacts D04 open to establish a circuit for thearmature DMA of the door operating motor through resistors RDMZ and RDM3to open the car door and also the hoistway door. As the doors move acertain distance, door speed limit switch DEL closes to complete acircuit for the coil of door speed switch DE. ContactsDES and DES engageto short circuit resistance RDMF in circuit with door moguards HPG torfield winding DMF and resistance RDMS in circuit with armature DMA,respectively. As the doors near open position, door speed limit switchDEL opens and door close'limit switch DCL closes without eiect, As thedoors reach open position, door open limit switch DOL opens todeenergize door open switch DO to break the circuit for armature DMA.Contacts D01 separate to deenergize door speed switch DE. Contacts DB4engage to establish a short circuit for armature DMA to bring the dooroperating motor to a stop.

Upon the expiration of a given time interval, auxiliary hall time relayXNT is deenergized. Contacts XNT3 separate to disconnect theVV coil ofhall time switch NT from the supply lines. Switch NT does not deenergizeimmediately, being delayed by the discharge of condenser QNT. ContactsNT2 close to establish a circuit by way of contactsfDRl for the resetcoil of door control switch DR which is restored to unlatched condition.Contacts NT2 also complete a circuit by way of door close limit switchDCL and contacts DPI and D02 for the coil of door close switch lDC toinitiate the door 'closing operation. A time interval is thus provided,namely the interval of relay XNT, Say three seconds, plus the intervalof switch NT, say another three seconds, or a total of six seconds, fromthe time that the stop is made before the closing of the doors isinitiated. This time interval is deiined as the door dwell period." Doorclose switch DC upon operation engages contacts DCZ and DC4 andseparates contacts DC3 to complete a circuitfor armature DMA to clos'ethe car door and hoistway door. As the doors move from fully openposition, limits'witch DOL recloses 'without effect at this time. Duringthe closing operation, limit switch DEL is again closed, causingoperation of door speed switch DE. Contacts DES close to shortY circuitmotor field resistance RDMF and contacts DB6 open to remove a shortcircuit for a portion of resistor RDMS. Asthe doors reach closedposition, door close limit switch DCL opens, breaking the circuit forthe coil of door close switch DC. Contacts DCZ and DC4 open to break thecircuit for the door motor armature DMA. Contacts DCI and switch DELopen to deenergize switch DE. Contacts DB4 reengage to establish a ShortcircuitV for armature DMA to bring the door operating motor to a stop.

The protective circuits of Figure 2 are effective only while the car isstopped due tothe provision of contacts H3. Referring tothe circuits fortube DPT, there isa capacity network from antenna CA tov shield CSG andIfrom antenna CA to ground. Thus a biasing voltage is applied to boththe control electrode DPTE and the conductive spot CS adjacent theanode, which bias is due to a direct current potential taken fromresistors RVDA, RVD and RVDB, andan alternating current potential whichis a function of the ratio of the two capacity networks. This isadjusted 'so that the biasing voltage is just below tube breakdownvalue. Resistor RIB lis of such value as to effectively isolate thealternating current source from the direct current source. When a personenters or leaves the Ycar his body capacity ineiect increases theantenna to ground capacity and thus brings the potential of theconductive spot and control electrode -toA which itl is connected nearerto ground potential. When during the closing of the doors antenna CAcomes within a predetermined distance of a person, the alternatingcurrent potential reaches a `value which causes breakdown of tube DPT.This 'completes the anode- 'cathode circuit of the tube which extendsthrough the coil of door protective relay DP, causing thisV relay tooperate. Upon operation, door protective relay DP causes the door tostop and then reopen as more fully described in connection with Figure 4of the Bruns Patent No. 2,634,828.

`In'order to minimize the chances of a person being hit by a closingdoor and to obtain an indication'of the failure of the protectivemechanism, the protective mechanism may be tested by causing tube DPT toconduct as if a person was detected in the path of the door.

.False operation of the protective mechanism toY test it may be causedby removing `the shield voltage applied to any' of the following:hoistwa'y-doorsight guard' HSG," ,a

post guard HPG, car door sight guard CSG, -and post guard CPG, or byincreasing the biasing voltage appliedy to conductive spot CS andelectrode DPTE.

In the preferred to lire is applied to the hoistway door sight guard HSGby closed contacts MRS which connect-the sight guard to a top ontransformer SGT. This reduced shield potential on the hoistway doorsight guard HSG has no etect ou the protective mechanism at this timesince brake contacts H3 are open while the car is running, as previouslymentioned. l

Incident to the car stopping at a floor, car running contacts FE1 openbut are not effective at this time, being bypassed by the self-holdingcircuits MR1 through DPXI and GHI. As the car stops at the floor,contacts H3 close to render the protective mechanism effective. As thedoors begin to open, door relay contacts GHI open without affectingmonitoring relay MR. The aforementioned reduced shield potential appliedto, HSG via the transformer SGT tap brings the antenna closer to groundand causes the tube to conduct energizing door protective relay DP.Contacts DPS close to energize auxiliary door protective relay DPX whichis delayed inv dropping out through contacts DPX4.

Contacts DPXI open to breakthe self-holding circuit of monitoring relayMR thereby rendering any subsequent actuation of contacts DPXI, GHI orXNT1 ineffective. Contacts MR4 close and contacts MRS open to apply fullshield potential to sight guard HSG, thereby removing the stimulant tofalse operation of the protective mechanism.

As the doorsbegin toppen, if the protective mechanism Ifails to operateunder the stimulation of reduced shield potential which approximates theeiect on the mechaf nism of the presence of a personin the path of theclosing` door, monitoring relay MR remainsenergized through self-holdingcircuit MRI, DPXI. Closed contacts. M R3 short circuit part of 'resistorRDM4 ina parallel with' door motor armatureDMA'to reduce the speed vofthe,V door closing.l At the expiration of the time interval of auxiliaryhall time relay XNT, contacts XNT1 close to maintain relay MR energized,even though during the door closing operation, tube DPT may conduct andcause contacts DPXI to separate. At the end of the door dwell periodcontacts NT1 close to complete the circuit to energize flicker relay FRthrough closed contacts MR2. Flicker relay contacts FRI and FR?. closeand open to flicker the lamp LP, corresponding to the floor at which thecar is stopped and to-ring buzzer BZ as an indication of the faultyoperation of the protective mechanism. The alarm condition and reduceddoor closingspeed, once initiated, is maintained until contacts NT1separate to break the circuit to ilicker relay FR as the car leaves thefloor.

Arrangements for monitoring the operation of other forms of door-protective mechanism may be employed. To illustrate this, examples ofother forms of door protective mechanism are illustrated in Figures 3and 4. These circuits are arranged to be used with the door oper# atingcircuits shown in Figure l below relay MR.'

Referring to Figure 3, the circuits there illustrated are for-the lightray type of protective mechanism suit# able for both sideopeningand'ce'nter opening doors.

vembodiment of the invention, the shield voltage applied to the hoistwaydoor sight guardv PHTI 'fand- 'PHTZ `'are indicative fof4 a pluralityofl photo tubes', such asth'e 918 type, positioned' on oneside vof thecar door entrance to scan an area of average person height'. Llvand'LZare pinpoint sources of light for the photo'tubesarranged onA theopposite side of the entrance in linerespectively with the photo tubesfor which l they are provided. The photo tubes are arranged to actthrough an amplifying tube AMT having its control gridY connected to thepoint X. This tube may be a pen'tode such as 6SJ7 to provide a highgain. The coil of safety mechanism switch B is in the anode-cathodecircuit of tube AMT. So long as the light ray for each tube PHT is notobstructed, a positive potential exists at point X to cause sutiicientcurrent flow through tube AMT to' operate safety mechanism switch B.Thus contactsv B2 are separated. Contacts H4 close-when the ca'r-V stopsat `ai licor `and lremain closed -until the car kdeparts from thatliioor. Upon' obstruction of one or more ofthe light rays by-passengertransfer, the potential at point X is reduced sufficiently to cause thedeenergization of 4safety mechanism switch B. Contacts B2 engage tocause operation of door protective relay DP which in turn engages con`tacts'DP4 to cause operation of auxiliary door protective relay DPX.Relays DP and DPX control the doory operating circuits of Figure l toprevent the then closing of the door or'if closing, to return it to openposition as described in Brunsv Patent No. 2,634,828. Also, if any ofthe light sources or photo cells are inoperative or tube AMT fails toconduct properly, contacts B2 engage to open the doors. In this case thedoorswill remain open after the door'dwell period has expired.

Referring now to Figures 1 and 3, while the car is running, monitoringrelay MR is energized through car running contacts FE1. Closed contactsMR6 insert the full value of resistor R1 in series with light sources L1and L2. The excitation for the light sources L1 and L2 is reduced to avalue which will bias tube AMT to conduct less current than the minimumcurrent requiredl tol maintain switch B energized. The sensitivity ofthe photo tubes PHTI and PHTZ is testedin this manner. Therefore, switchB is in deenergized condition while the car is running. Contacts B2 arenot effective at this time since the circuits of relays DP and DPX areinoperative auxiliary hall time relay XNT, as previously mentioned.-

When the car slows fdown, contacts FE1 open'without aifecting relay MRdue to self-holding circuit MRI, GHI.l As the doors begin to open priorto the car coming to a stop, contacts GHI separate breaking the circuitof relay MR through self-holding contacts MRI. 1 Contacts 'MR open andcontacts'MR7 close to-short circuit part of re-l sistor R1 to apply fullvoltage to light sources L1 and L2. The bias of tube AMT is reducedcausing it to conduct and energize switch B. As the car stops, contactsH4 close putting the door protective mechanism into opera-Y tion.Contacts B1 close without effect since contacts MRI are already open. y'I As the doors begin to open, although the excitation of the lightsources L1 and L2 isreduced, as previously de# scribed, the protectivemechanism may fail to' false operate. This failure may be due to tubeAMT continuing to conduct, relay B failing to deenergizeor contacts`B2being stuclt together. Whatever the reason for the failure may be, ifcontacts VB1 are closed, as contacts FE1 open and contatcs GHI separateincident to the car slowdown and the door opening, relay vMR remainsenergized. At the expiration of the time interval of auxiliary hall timerelay XNT, contacts XNT1 close to maintain relay MRene'rgized. `At theexpiration of the door dwell period, the door closes at reduced speedand an audible and visual alarm is initiated, as previous-r lydescribed.v r'Without this described pretest of the protectivemechanism,y if. during closing movement of the door-the light beam is`interrupted, with contacts B2 stuck 7 together, the door will continueto close at full normal doorV 'closing speed with the protective`mechanism inoperative. Y f

Referring to Figure 4, the door protective `circuits therein lustratedare based on the circuits of Figure of the patent to Lubkin No.1,982,442 granted November 27,

contacts GHl separate incident to c arj slowdown and door opening, relayMR remains energized. Contacts XNTI 1934. A capacitor Q50 made up oftrough TRSI and plate PLS'S extends vertically over a scanning areaalong the front edge of the car door. Q62 is a shielded compensatingcondenser variable in accordance with the position of the doors forvpreventing unwanted operations. Connections to one side of capacitor Q50andcondenser Q62 are led through shielded cables to box B061. This box,the shield for condenser Q62, the cable sheaths, the other side ofcondenser Q62 and capacitor Q50 are connected to ground. Within box B061is a triode vacuum tube OST86 with its grid and anode connected to atuned circuit made up of` condenser Q88 and inductance 1N87, this beingutilized to generate high frequency oscillations. RET96 is a triodevacuum tube with its input circuit conducted across inductance I l104.The coil of switch B is connected in the anode-cathode circuit of tubeRET96. Inductances IN87 and IN104 are inductively coupled so that thegenerated high frequency oscillations are induced in inductance INI04.In parallel with inductance INI04 are capacitors Q50 and Q62 to form inconjunction with condenser QI13 a tuned circuit TC112. Condenser Q116 inparallel with condenser Q50 is prevented from affecting tuned circuitTC112 during normal operation of the door protective mechanism by opencontacts MRS, whose operation will be explained later. With no person inthe entranceway the tuned circuit is in resonance with the generatedhigh frequency oscillations causing sufficient current flow in the coilof switch B to maintain this switch in operated condition. When a personor object in the entranceway alters the electrostatic eld due tocapacitor Q50 and thus detunes the tuned circuit TC112 from resonancewith the generated oscillations, the current flow is reducedsufficiently to cause switch B to deenergize and complete the circuitfor the coil of relay DP. As previously explained, this relay controlsthe door operating circuits to prevent the then closing of the door orif closing, to return it to open position.

Referring to Figures l and 4, while the car is running, monitoring relayMR is energized through car running contacts FEI and is maintainedenergized through selfholding circuit MRI, GHI. Closed contacts MRSconneet condenser Q1\16 in parallel with condenser Q50 of tuned circuitTC112. Condenser Q116 has a value of capacity selected to approximatethe effect of the body capacity of a person in the path of a closingdoor at a predetermined distance from the front edge of that car door oncapacitor Q50. This selected value of capacity is sucient to detune thetuned circuit TC112 from resonance with the generated oscillations.Thus, current ow is reduced suiciently to cause switch B to deenergize.The operation of the protective mechanism is tested at a predeterminedlevel of sensitivity -in this manner. Contacts B1 are not effective atthis time since the circuits of relays DP and DPX are inoperative due toopen contacts H4. When the car slows down, contacts FE1 open without`affecting relay MR. As the doors begin to open prior to the car comingto a stop, contacts GHI separate breaking the circuit relay MR throughself-holding contacts MRI. Contacts MRS open removing condenser Q116from thecircuit of T0112, returning that circuit to resonance with thegenerated oscillations to cause sufficient currentto ow in the platecircuit of tube RET96 to energize switch B. As the car stops, contactsH4 close putting the door protective mechanism into operation. ContactsB2 close without effect since contacts MRI are already open. Withcondenser Q116 disconnected, as previously described, if contacts B2remain closed to indicate a failure of the protective mechanism, .ascontacts FE1 open and 7.5

close ,at the expiration of the auxiliary hall time relay time interval.Relay MR controls the door operating circuits ,to reduce the closingspeed of the door and initiate an alarm indication, which once initiatedis maintained by closed contacts XNTI, as previously explained.

p Anarrangement for monitoring the operation of still another form ofdoor protective mechanism is illustrated in Figure 5. This circuit isarranged to be used with the door operating circuits shown inFigure 1,wherein all contacts designated DPX are to be considered contactsdesignated DP. The circuits of Figure 5, with the exception ofmonitoring antenna MA are the subject matter of the yco-pendingapplication of Lew H. Diamond, etal., Serial No. 697,370, iied November19, 1957. TRBI and TRBZ designate transformers. AMI to AM3 designateamplifiers. VDI and VD2 designate voltage doublers. PI and P2 designatepotentiometers. An alternating voltage source is connected from line BOto ground G, this source being indicated hy block OSC. The anodcs ofamplifier tubes AT1, ATZ are connected to supply line B+. Current forthe coil of relay DP is provided from alternating current supply linesAC1, ACZ. The four antennae UA1, UA2, LAI and LA2 form capacitances toground. They are arranged in pairs and are positioned one above theother along the leading edge of the car door.

The antennae of each pair are connected directly to the opposite side ofthe diagonal of a bridge, with each antenna connected in a differentbridge circuit from the one in which is connected the next succeedingantenna. Each bridge is adjusted to provide substantially zero voltageacross its diagonal w'nen no object, such as a person, sought to beprotected, is in the field of inuence of the antennae connected lin thatbridge. When such person comes into the ield of influence of one or moreantennae, there is sufi'lcient change in capacity in one leg withrespect to the other of one or more bridges to cause a suicient signalvoltage to appear across the diagonal of the bridge, which whenampliiied energizes relay DP. Relay DP in turn is caused to operatemechanism to bring the door to a stop if closing or to prevent itsclosing if it is in open position.

Monitoring antenna MA is provided to span the two centrally locatedantennae UA2 and LAI, and is rendered effective during each initial dooropening operation to cause sufficient decrease in impedance of oneantenna of each bridge to ground to cause operation of relay DP. Bymeans of door limit switches DLI and DL2, the monitoring antenna isconnected to line BO while the doors are in closed position and in openposition and during door closing, thereby rendering the monitoringantenna ineffective to cause operation of relay DP during this time.Monitoring antenna MA is connected to line BO by shielded cable, withthe shield, not shown, connected to ground. During the initial dooropening operation, when the car stops at a oor, these limit switchesdisconnect the monitoring antenna from line BO, enabling the antenna bymeans ofthe capacitance coupling to ground of its wire in the groundedcable to bring ground potential sufficiently near the center antennaeUA2 and LAI to cause operation of relay DP.

Limit switch DLI is a toggle switch which opens when the door reachesapproximately one-quarter inch of closed position and remains open untilthe door reaches approxi- 'mately one-quarter inch of open position, atwhich point it closes and remains closed until the door again reaches,roughly, one-quarter inch of closed position. Limit switch DL2 is set toopen at approximately one-half inch of door opening movement and closeas the door arrives approximately within one-half inch of fully openposition.

When the door starts to open ata floor at which a stop is being made,limit switch DL2 opens, disconnecting monitoring antenna'MA ,from lineBO. Assume that the detecting mechanismis'functioning properly, Vthiscauses operation of relay DP to open contacts DPXI (Figure l)l openingoperation, relay MR remains energized to close the door at slow speedand initiate an alarm as-previously explained, advisingthat thedetecting mechanism is not functioning properly. 1 v Asmany changescould be made in the above construction and many apparently Widelydifferent embodiments of this invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing shall beinterpreted as illustrated and not in a limiting sense.

What is claimed is: 1. In a control for opening and closing an elevatordoor, door actuating means for moving said door in an opening directionat a given speed and for closing s aid door at either of twopredetermined speeds, protective mechanism responsive to the presence ofan object in the path of the door duringV its closing movement andeffective to control further movement of said door, testing meansnormally adapted to actuate said protective mecha-` nism momentarily toits operated condition during the opening of said door, and controlmeans operatively responsive to the operationof said protectivemechanism in responsevto said testingmeans for causing said dooractuating means to close said door at the slower of said twopredetermined speeds under conditions where said protective mechanismfails to operate in response to said testing means and to close saiddoor at the other of said speeds under conditions where said protectivemechanism operates in response to said testing means.

2. In a control for an elevator door in which power actuated mechanismmoves said door in its opening and closing movement, said closingmovement being in accordance with either of two predetermined modes ofoperation, protective mechanism mounted on said door responsive to thepresence of an object in the closing path of the door and effective tocontrol subsequent movement of said door, testing means operative duringthe opening movement of said door for subjecting said protectivemechanism to controlled conditions designed to cause its actuation, andcontrol means operatively responsive to the reaction of said protectivemechanism to said controlled test conditions andetfective to cause saidpower actuated mechanism to close said door in accordance with one ofsaid two predetermined modes of operation and effective to the lack ofreaction of said protective mechanism to said controlled test conditionsto cause said power actuated mechanism to close said door in accordancewith the other of said two predetermined modes of operation.

3. In combination, an elevator door control, said door control havingprotective mechanism'etfective when actuated to cause stopping of theelevator door during its closing movement, testing means effective totest the operation of said protective mechanism incident to the carstopping at al iloor landing, and circuit controlling means operablefrom a lirst condition to a second condition, said circuit controllingmeans when in said rst condition being to reduce the speed of closingsaid door below normal closing speed, said circuit controlling meansbeing actuated to said second condition by said operation of saidprotective mechanism in response to said testing means.

false operation to render said `4. In-combination, an elevator doorcontrol, 'sa'iddobri control having protective mechanism for stoppingthe elevator door during its closing movement, alarm initiating means,means for reducing the speed of the door during its closing movement,testing means to test the operation of said protective mechanismincident to the car stop` ping at a floor, and circuit controlling meanslresponsive to initial door opening and actuable by operation of saidprotective mechanism in response to said test by said testing means torender said alarm initiating means, said speed reducing means and saidtesting means inoperative.

5. In a control for a door of an elevator car in which mechanism isprovided wihich is responsive to an object being in the path of saiddoor to detect the presence of said object before striking said object,testing means actuated incident to the car stopping at a floor landingmomentarily to stimulate false operation of said detecting mechanism totest the operation thereof, door-open means, door-close means, timingmeans to cause said door-close and said door-open means to establish aperiod during which the door remains open at a floor land- -ing to eectpassenger transfer, alarm initiating means operably controlled by saidtesting means and said timing means for initiating an alarm at the endof said period under conditions where no such false operation of saiddetecting mechanism occurs, and means to reduce they speed of the doorin closing operably controlled by said testing means, said testing meansbeing responsive to said alarm initiating means and said'speed reducingmeans inoperative.

' 6.A monitoring and alarm initiating device for use with a control o fthe door of an elevator car, said car serving several floors of abuilding, said control including protective mechanism to limit the forcewith which the door strikes an object in its path w 'le said door isclosing, said device comprising, protective-mechanism-actuatingmeans-operable incident to the car stopping at any of said oors inresponse to a call to causeoperation of said protective mechanism,detectingV means responsive to such operation of said protectivemechanism by said ac-v tuating means, such door-close speed reducingmeans, audible and-visual alarm initiating means for initiating an alarmas said door begins closing, said audible and visual alarm initiatingmeans and said door-close speed reducing means being renderedinoperative by operation of said detecting means, and means to maintainthe alarm and reduced door closing speed, once initiated, until the doorreaches its fully closed position.

7. An elevator installation in which an entrance-way is provided for theelevator car, in which a door is provided for said entrance-way, inwhich power mechanism including a reversible direct current motor isprovided for operating said door, in which switching means is providedfor variably connecting the armature of said motor to a source of directcurrent to cause operation of said mechanism to open and close saiddoor, and in which safety mechanism responsive to the presence of aperson in said entrance-Way is provided for causing operation of saidswitching means to disconnect said armature from said source therebydiscontinuing the closing operation of said door by said powermechanism; characterized in that second switch means is provided tocause said safety mechanism to be actuated momentarily during theopening cycle of said door, that alarm initiating means is provided toinitiate an alarm, that circuit controlling means is provided to reducethe amount of direct current to said armature to cause the door to closeat a speed slower than normal closing speed, and that disabling meansresponsive to actuation of said safety mechanism by said secondswitching means is provided for rendering said circuit controlling meansand said alarm initiating means inoperative upon such actuation of saidsafety mechanism.

8. In an elevator installation in which the elevator car is providedwith a door, in which a hoistway door is of said car door and saidhoistway door and vertically substantially from the oor of the car toscan a person of average height, each tube having a control connected toits antenna, in which means for applying direct current voltage to theanode-cathode circuits of said tubes of a value above the sustainingvoltage of the tubes but insuicient to break down the tubes is provided,in which means for applying alternating current potential with respectto ground to a point in the anode-cathode circuit of each tube and tosaid sight guard isY provided, said alternating current potentialapplied to said sight guard causing said sight guard to shield saidtubes and antenna against unwanted firing of said tubes by groundpotential on said car door and in addition causing each antenna to havean alternating current potential of a value determined by the ratio ofthe antenna to ground capacity to the sight guard to antenna capacity,said potential of each antenna being insuflicient to ire the tube forwhich the antenna is provided but upon a person moving into the zone ofinfluence of s uch antenna to increase the antenna to ground capacitybeing brought suiciently near ground potential to lire such tube, inwhich switching means is provided responsive to the ring of any tube toprevent operation of said power operating mechanism to close said doors,in which a sight guard is provided for each hoistway door electricallyinsulated therefrom, and in which means for applying to said hoistwaydoor sight guards alternating current potential with respect to groundin phase with the potential applied to said carv door sight guard isprovided to prevent unwanted iring of said tubes by ground potential ofsaid hoistway doors, characterized in that circuit controlling means toreduce said alternating current potential applied to said hoistway doorsight guard to a value slightly below the value necessary to preventunwanted tiring of any of said tubes by ground potential on saidhoistway doors is provided to cause any of said tubes to fire and saidswitching means to be actuated incident to the opening of said car andhoisting doors at a oor, means to cause said door to close at a slowerthan normal closing speed is provided, and means to initiate an alarm isprovided, said means to cause said door to close at a slower than normalclosing speed and said means to initiate an alarm being renderedinactive if said tube is caused to re by said reduction of saidpotential applied to said hoistway door sight guard.

V9. In combination with a control for the door of an elevator carserving several oors of a building, said car having an entrance-way,said control having light ray type protective mechanism, in which alight source emits a light beam, in which said'light beam is directedacross said entrance-way upon a photo cell to cause conduction in saidphoto cell, in which interruption of said light beam by an object in thepath of the elevator door causes said door control to stop said doorduring its closing movement to avoid striking said object, means toreduce the intensity of said light beam incident to the car stopping ata loor in response to a call to cause said protective mechanism to beactuated, means to reduce the speed of closing said door underconditions where said protective mechanism is unactuated by saidintensity reducing means, and means to initiate an alarm underconditions where said protective mechanism is so unactuated, said meansto reduce the intensity, said means to reduce the'speed of closing andsaid means to initiate an alarm being disabled as said protectivemechanism is so actuated.

Referencesy Cited inthe file of this patent UNITED STATES PATENTS2,634,828l Bums v-- Apr. 14, 1953 2,695,991 Atkinson Nov. 3o, 19542,785,392 Sorensen Mar. 12, 1957

